Earth Orbit Tilted By Rogue Star, New Research Suggets

One young star may yank another's developing solar system, a new theory suggests, accounting for planets that circle their stars on tilted paths. This idea may also explain a long-standing puzzle close to home: why Earth's orbit is tipped 7° relative to the sun's equator.

One other multiplanet solar system has a known tilt: our own. "I think somewhere in the Milky Way, there's a star that's responsible for tilting us," Batygin says. He suspects the sun once had a companion star that tipped the solar nebula by 7°, then fled the scene after the planets arose.